Three-dimensional reconstruction of the rat nephron.

This study gives a three-dimensional (3D) structural analysis of rat nephrons and their connections to collecting ducts. Approximately 4,500 2.5-µm-thick serial sections from the renal surface to the papillary tip were obtained from each of 3 kidneys of Wistar rats. Digital images were recorded and aligned into three image stacks and traced from image to image. Short-loop nephrons (SLNs), long-loop nephrons (LLNs), and collecting ducts (CDs) were reconstructed in 3D. We identified a well-defined boundary between the outer stripe and the inner stripe of the outer medulla corresponding to the transition of descending thick limbs to descending thin limbs and between the inner stripe and the inner medulla, i.e., the transition of ascending thin limbs into ascending thick limbs of LLNs. In all nephrons, a mosaic pattern of proximal tubule (PT) cells and descending thin limb (DTL) cells was observed at the transition between the PT and the DTL. The course of the LLNs revealed tortuous proximal "straight" tubules and winding of the DTLs within the outer half of the inner stripe. The localization of loop bends of SLNs in the inner stripe of the outer medulla and the bends of LLNs in the inner medulla reflected the localization of their glomeruli; i.e., the deeper the glomerulus, the deeper the bend. Each CD drained approximately three to six nephrons with a different pattern than previously established in mice. This information will provide a basis for evaluation of structural changes within nephrons as a result of physiological or pharmaceutical intervention.

Destructive, granulating lesion in the temporal bone after elevated plasma homocysteine.

OBJECTIVE: This is a presentation of a seemingly new otolaryngologic disease. SETTING: This study was conducted at a tertiary referral center. CASE REPORT: A 38-year-old healthy man developed left-sided sudden deafness with vertigo and temporary left facial palsy. A granulating and destructive lesion in the left temporal bone was discovered; repeated histologic examination only showed simple granulation tissue. After 6 months, a part of the bony cochlea was extruded. With approximately 8 months' delay and after the patient had had postoperative lung embolism, plasma homocysteine was found to be significantly elevated, a condition known as an independent risk factor for thromboembolic lesions. In the acquired form, it is most often caused by nutritional deficiency of vitamin B cofactors. Accordingly, the patient was treated with folic acid, which rapidly normalized plasma homocysteine. Subsequently, the granulation tissue in the temporal bone gradually disappeared, clinically and radiologically, and the lesion healed, obviously without cochlea function. CONCLUSIONS: Thromboembolic lesion in the left temporal bone, probably in the thin end artery a. labyrintina, i.e., an avascular osteonecrosis. During the latest years, an association between avascular osteonecrosis (most often in the hip) and conditions with increased risk of thrombosis such as hyperhomocystinemia has been established but, to the best of our knowledge, it is never with a lesion in the temporal bone.

Brothers with Chudley-McCullough syndrome: sensorineural deafness, agenesis of the corpus callosum, and other structural brain abnormalities.

We describe two brothers with Chudley-McCullough syndrome who are 5 and 17 years old. They were born to healthy consanguineous parents of Pakistani descent. They had severe sensorineural deafness and neuroimaging showed corpus callosum agenesis and other structural brain abnormalities. The Chudley-McCullough syndrome is an autosomal recessive disorder, first described by Chudley et al. [1997: Am J Med Genet 68:350-356]. The original description of the syndrome includes hydrocephalus due to obstruction of the foramen of Monro and early-onset severe to profound sensorineural deafness. We review the findings in the two patients we describe, four children reported in the literature and two patients reported by Hendriks et al. [1999: Am J Med Genet 86:183-186] with sensorineural deafness, corpus callosum agenesis, and interhemispheric cysts, who may well have Chudley-McCullough syndrome. All patients had sensorineural deafness. The neuroimagings of all eight patients showed colpocephaly, which is most likely caused by corpus callosum agenesis. Three patients had other structural brain abnormalities: cortical dysplasia and gray matter heterotopia. We suggest a revision of the clinical description since the most likely basic developmental defect is corpus callosum agenesis and not foramen of Monro obstruction.